(A) The city reserves the right to develop or adopt guidance documents to serve as design and implementation standards. Other guidance documents distributed by the city should be reviewed and considered when preparing the post-construction SWMP. Technical, administrative, or procedural matters may be modified as needed to meet the objectives defined in this chapter so long as they are not contrary or beyond the intent of the objectives listed above. Such documents given authority by this chapter include best management practice (BMP) manuals, design regulations and requirements, checklists that address submittals, plan review, and inspections, certifications, stormwater manuals, and operation and maintenance manuals. The documents may be updated periodically to reflect the most current and effective design and construction practices and be made available to the public. Failure to update the manual does not relieve the applicant from complying with this chapter.
(B) Post-construction stormwater BMPs shall be designed in accordance with the most current manual or requirements to achieve the following performance standards:
(1) Water quality of stormwater produced from the 80th percentile rain event shall be addressed with best management measures that are built and maintained to treat, filter, flocculate, infiltrate, screen, evapo-transpire, harvest and reuse stormwater runoff, or otherwise manage the runoff for all new and redeveloped sites. (The 80% rain event is based on past rainfall data and will continually change with future rain events, however, it is not anticipated to vary drastically from one year to another).
(2) BMPs shall be designed to remove pollutants and reduce runoff volume. The designated use and any existing in-stream use of the stream being discharged to shall be protected. Some land uses produce higher concentrations of certain pollutants such as hydrocarbons or heavy metals, than those normally found in urban areas. These areas will be reviewed for effective removal of the particular pollutant which they discharge. Effective removal will be that which existed prior to development. Examples of land uses that produce higher levels of pollutants are:
(a) Gas/fueling Stations;
(b) Restaurant dumpster areas;
(c) Vehicle repair facilities;
(d) Vehicle washing/steam cleaning facilities;
(e) Auto recycling facilities;
(f) Outdoor material storage areas;
(g) Loading and transfer areas;
(h) Landfills; and
(i) Industrial sites.
(3) BMPs shall reduce or buffer increases in stormwater runoff temperature caused by contact with impervious surfaces as well as minimize increases in stormwater runoff volume and flow rate caused by increases in impervious surfaces.
(4) The PC-SWMP shall include provisions for buffer zones. A buffer zone shall be defined as:
(a) Area contained within a boundary established by the FEMA floodplain boundary; or
(b) Where a floodplain is not defined or calculated, the buffer will be 25 feet on each side from the top of waterway bank as defined by geomorphic shape (not by current water surface elevation).
1. Buffers shall be provided to all blue-line streams as shown on the USGS map.
2. Buffer areas and floodplain may be used for stormwater quality devices provided erosion prevention, sediment control, cut-fill practices are addressed appropriately as determined by the city to meet this chapter.
3. Exemptions can be granted to buffers so long as erosion and sediment control, water quality are addressed. Exemptions for building in the buffer area shall be granted for:
a. Roads and utilities crossing waterways.
b. Pedestrian trails and walkways adjacent to waterways.
c. Other exemptions may be made at the discretion of the City Civil Engineer.
(5) (a) Redevelopment not previously addressing water quantity or quality control shall reduce the discharge from their site according to the formula below:
Q(redeveloped) = Q(existing) + Q(undeveloped)
2
2
Q(redeveloped) = maximum discharge rate for the re-development
Q(existing) = current discharge rate of the developed parcel
Q(undeveloped) = discharge rate of the parcel prior to any development
(b) The reduction of allowable flow rate for redeveloped areas shall not exceed more than 30% of the existing developed flow rate. These flow rates are based on redevelopment sites that disturb one acre or more.
(6) The City of Bardstown reserves the right to require additional treatment criteria or objectives for specific pollutant(s) as necessary to meet overall stormwater quality management program objectives or directives under a watershed improvement or Total Maximum Daily Load (TMDL) program as administered by the USEPA and/or the Kentucky Division of Water.
(7) For projects that cannot meet the above quality criteria, they may choose either of the following options:
(a) Off-site mitigation option: entails infiltration/ evapotranspiration/reuse measures that may be implemented at another location within the same watershed as the original project approved by the city. The city shall identify priority areas within the watershed in which mitigation projects can be completed.
(b) Payment-in-lieu option: allows the owner of a project that falls within the quality criteria, to make a payment to the city in lieu of implementing post-construction BMPs. The city will apply the in-lieu funds to a public stormwater project. The fee shall be used for acquisition, design, construction, or maintenance of one or more such facilities in the same watershed in which the development is located.
(8) Permanent easements for all stormwater drainage ways, quality and quantity facilities shall be dedicated to the city and recorded in the Nelson County Clerk’s Office. There shall also be dedicated easements for access to all stormwater management facilities.
(Ord. B2011-19, passed 9-27-11)